Preheat the oven to 200C, 400F, gas mark 6.
Place cake cases into a 12 hole cake tin. Sift the
flour, cocoa, baking powder and cinnamon into a large
bowl. Stir in the sugar and 125g (4.5 oz) of the white
chocolate. Whisk together the eggs and oil in a separate
bowl until frothy, then slowly whisk in the milk. Stir
into the dry ingredients until blended. Spoon into
cake cases, filling each to three-quarters full. Bake
in the oven for 20 minutes. When cool, melt the remaining
white chocolate over a bowl of simmering water and
spread over each muffin. Leave to set, then dust the
tops of the Double Chocolate Muffins with cocoa powder.